Known arrangements having a changeable focal width that are used, for example, for the imaging of tilt mirror matrices differ essentially in the number of optical elements (lenses), their arrangement in the device as a whole, as well as the technical design data, in combination with the conditions that apply for the optical system. Such arrangements are described, for example, in U.S. Pat. No. 5,644,435 and DE 69328891.
Since it is desirable for the most frequent applications to change the size and the location of the image in order to thereby adapt the projection to the most varied spatial conditions, projection zoom systems are primarily used.
Such arrangements often use many lens elements and are therefore highly cost-intensive. Furthermore, different zoom movements have to be implemented. This has the result that the arrangements have a very complex structure, and therefore no small construction sizes, in terms of diameter and construction length, can be implemented.